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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
551

Chlordécone et filières animales antillaises : de la distribution tissulaire aux stratégies de décontamination chez les ruminants / Chlordecone and livestock in the French West Indies : From the tissue distribution to the decontamination strategies in ruminants

Lastel, Marie-Laure 16 December 2015 (has links)
La CLD est un composé toxique qui (i) pollue plus de 15% des surfaces agricoles de la Guadeloupe et de la Martinique, (ii) résiste à la dégradation biotique et abiotique, (iii) s’accumule le long de la chaine alimentaire et dont la disparition des sols par lessivage est estimée à plusieurs centaines d’années. Les animaux de rente originaires de ces zones polluées sont contaminés et l’état de l’art a révélé un manque d’information évident sur le comportement de la CLD dans l’organisme de ces animaux et moins de dix publications sur leur décontamination. Deux protocoles expérimentaux ont été conduits sur des caprins mâles en croissance afin de caractériser le comportement de la CLD dans l’organisme des ruminants non lactants et de développer des méthodes optimisant leurs processus de décontamination. Les résultats ont montré que (i) les chevreaux éliminaient plus de 70% de leur CLD tissulaire après 3 à 4 semaines de décontamination et (ii) ni leur état d’engraissement initial ni l’ajout de charbon actif ou d’huile de paraffine dans leur alimentation ne modifiaient ces taux d’excrétion. Ces études ont également montré que la CLD se comportait différemment des autres polluants lipophiles car sa concentration tissulaire (exprimée sur la base de la matière grasse) était plus importante dans le foie et les muscles des animaux contaminés que dans leurs tissus gras. Ces résultats soulèvent des questions sur les mécanismes à l'origine de la distribution tissulaire de la CLD, son métabolisme et sur l’interaction de ce dernier avec le cycle entéro-hépatique. La compréhension de ces processus permettra de mieux ajuster les stratégies de décontamination pour les rendre plus efficaces / Chlordecone (CLD) is a toxic molecule which (i) contaminates more than 15% of agricultural land in Guadeloupe and Martinique islands, (ii) resists to biotic and abiotic degradation, (iii) accumulates along the food chain and whose the disappearance by soil leaching is estimated at several hundred years. The contamination of livestock in polluted areas is a health, social and economic issue. A literature review on CLD revealed a crying lack of information on its behavior in livestock’s organism and currently, there are less than ten studies which deal with livestock’s decontamination. Two experimental protocols were developed to characterize the behavior of CLD in ruminants’ organism and to evaluate methods that can optimize the decontamination processes of these animals. Results showed that all animals have eliminated more than 70% of Chlordecone in 3 to 4 weeks and neither the initial kids’ body fatness nor the addition of activated carbon or the addition of paraffin oil in the diet during the decontamination period altered these rates of excretion. Following these studies, the lipophilic behavior of CLD in animals is, also, questioned because the results showed that the concentrations of this pollutant, expressed on the fat matter basis, were higher in the liver and the muscles than in the peri-renal fat. These results raised new questions: firstly, on the mechanisms which control the CLD tissue distribution and secondly, on the role of the CLD metabolism and its interaction with the entero-hepatic cycle. The understanding of these processes should help to better adjust the decontamination strategies in order to make them more efficient
552

Anaemia in East African short-horn Zebu calves : field diagnosis, infectious causes and pathogen interactions

Conradie van Wyk, Ilana 18 September 2012 (has links)
This study formed part of the collaborative IDEAL (Infectious Diseases of East African Livestock) project, which focused on the sedentary mixed crop-livestock smallholding system in Western Kenya. This was a longitudinal study where calves were recruited at birth and followed at 5-weekly intervals until 51 weeks of age. The main aim was to investigate the total disease burden of cattle in the study area for the first year of life. The main objectives of the study concerned anaemia as a syndrome in the calves. Anaemia can provisionally be diagnosed based on clinical signs, but a confirmatory diagnosis is based on measuring of red blood cell parameters, such as packed cell volume (PCV), red cell counts (RCC) or haemoglobin (HGB). The FAMACHA / Thesis (PhD)--University of Pretoria, 2012. / Veterinary Tropical Diseases / unrestricted
553

Serological response of cattle vaccinated with a bivalent (SAT 1 and SAT 2) foot-and-mouth disease vaccine in Gaza Province, Mozambique

Massicame, Zacarias Elias 21 November 2012 (has links)
Foot-and-mouth disease (FMD) is a viral disease endemic in Africa, the Middle East, South America, Asia and parts of Eastern Europe. It is a major constraint to international trade in livestock and livestock products in many African countries. In southern Africa, African buffaloes (Syncerus caffer) are reservoirs of the South African Territories (SAT) 1, SAT 2 and SAT 3 FMD viruses, and cattle raised in the vicinity of wildlife conservation areas are at constant risk of becoming infected with FMD viruses. In Mozambique, control of FMD is fundamentally based on vaccination of cattle in zones around protected areas. However, the vaccination protocol recommended by the vaccine producer (two primary vaccinations followed by four- to six-monthly boosters) is logistically impractical and financially not suitable for most countries. As a result, the double primary vaccination is usually not implemented. A commercially available bivalent FMD vaccine, containing the SAT 1 and SAT 2 serotypes, was assessed for its ability to induce and sustain immunity in cattle for at least 6 months following a single primary inoculation. The study was conducted with cattle reared in Limpopo National Park (LNP), Mozambique, and adjacent areas. One hundred and seventy five seronegative cattle aged between 6 and 18 months were vaccinated and 42 others from the same areas were left unvaccinated, as controls. A group of 39 vaccinated cattle were revaccinated 4 months after initial vaccination and 63 others were revaccinated 6 months after initial vaccination. The vaccinated and unvaccinated cattle were bled at predefined intervals (at vaccination, and at 1, 4, 5, 6, 8, 10 and 12 months post vaccination) and sera were tested with a liquid phase blocking ELISA to measure the antibody level against FMD virus. A high proportion (73%) of vaccinated cattle had seroconverted (log10 titre ≥1.6 for any SAT serotype) at one month after vaccination with a single primary dose and there was no significant difference between the proportions of animals that seroconverted to SAT 1 compared to SAT 2. A higher proportion of animals within LNP (82%) than outside LNP (50%) had seroconverted at one month after vaccination (P = 0.001). Overall, however, only relatively few animals (27% for SAT 1, 35% for SAT 2 and 7% for SAT 3) had protective antibody titres (log10 titre ≥2). At 4 months after vaccination, a very low proportion (8.3%) of vaccinated cattle had antibody titres ≥1.6 to any of the SAT serotypes, and there was no significant difference between the proportions of animals with antibodies to SAT 1 (2.1%) compared to SAT 2 (7.3%) (P = 0.17). No cattle had a protective titre (≥2) to SAT 1 at 4 months and only 4.2% to SAT 2. The revaccination at 4 months after initial vaccination elicited antibody titres ≥1.6 in 22% of vaccinated animals at one month after revaccination; this rose two months later to 90% and remained high (91%) at 10 months post first vaccination before dropping to 65% at 12 months. However, only 15% of cattle had protective titres (≥2) to any of the SAT serotypes at 12 months. For cattle revaccinated at 6 months after first vaccination the percentage of cattle that had a titre ≥1.6 two months after revaccination was also high (80%), remained high (89%) at 10 months post first vaccination and dropped to 54% at 12 months after first vaccination. Only 11% of cattle had protective titres (≥2) at 12 months. The research findings indicate that, although the vaccine is able to induce production of antibodies against SAT 1 and 2 in a significant percentage of cattle within one month after a single primary vaccination, these antibodies are short lived and have largely disappeared by 4 months post vaccination. This suggests that a protocol of a single primary vaccination is inadequate in naïve animals, even if revaccination takes place four months later. Revaccination improved the immune response for a longer period, resulting in detectible titres in the majority of animals for 6-8 months post revaccination. This can be used in disease control programmes to ensure some protection of cattle particularly when it is applied immediately before identified high risk periods of occurrence of FMD outbreaks. However, it seems unlikely that six-monthly revaccination is sufficient to maintain adequate levels of protective immunity. The study highlighted several difficulties associated with the vaccination of livestock under field conditions and the conduction of field trials. These included difficulties with cold chain maintenance, poor infrastructure for animal handling, and loss of follow-up due to loss of animal identification or poor owner/herder compliance. Copyright / Dissertation (MSc)--University of Pretoria, 2012. / Production Animal Studies / unrestricted
554

Investigations of the Theileria parva carrier-state in cattle at the livestock/wildlife interface of the uPhongolo-Mkuze area in KwaZulu Natal, South Africa

Mbizeni, Sikhumbuzo 21 November 2012 (has links)
Corridor disease (Theileria parva infection in cattle associated with carrier buffaloes) was not reported to cause serious outbreaks prior to 1994. From 2002-2004, outbreaks in cattle have increased in the areas where the disease is endemic in buffalo populations. In this study, the occurrence of Corridor disease outbreaks in the Zululand district municipality was closely monitored from 2004-2009. The observations included the number of cattle involved in the outbreaks, clinical signs, parasitological and post-mortem examinations while blood for serum and in EDTA were collected for serological (IFA test) and molecular (real-time PCR) tests specific for T. parva. Samples were collected from cattle involved in the outbreak, the sick and presumed recovered cattle. Recovered cattle from the farms were brought to the laboratory at the Onderstepoort Veterinary Institute for further investigations. This included tick pick-up and transmission attempts to demonstrate their carrier status as well as assessing their immunity to further experimental challenge using virulent T. parva stabilate. Results were obtained on Corridor disease outbreaks in the study area and ad hoc locations comprising a total of 15 commercial farms and community diptanks in the district from 2004 to 2009. A total of 31 outbreaks were recorded during the study period. The number of outbreaks per year was stable, being 3 or 4 from 2004 to 2007. A 100 percent increase was recorded in the subsequent years, 2008-2009. In one location, Morgenzon farm comprising a commercial and community farmers, had experienced regular outbreaks from 2004-2009. It is also noted that some farms experienced outbreaks for three consecutive years. Three other farms had experienced outbreaks for the first time in either 2008 or 2009. The most severe outbreak occurred in Nyalisa in 2009 where the disease was experienced for the first time in one herd in which 202 cattle were involved and 57 died within 30-40 days after the onset of the disease. Using all the tools mentioned above, the cause of death was confirmed to be due to T. parva infection. The Corridor disease outbreaks that were investigated, have mostly been reported during the months from March-May (88 %) but some (8 %) were encountered during the winter months (June-August). The distribution of outbreaks mainly coincided with the activity period of adult R. appendiculatus. During the investigation period, a total of 846 cattle were tested for Corridor disease and the prevalence was found to be 27 %. The percentage of cattle which were found positive by PCR was 16.5. Seven percent were found positive on both PCR and IFA tests, an indication of the development of a carrier state. However, 10 % of the cattle remained sero-positive with no indication of being parasite-carriers (real-time PCR negative). Five cattle which recovered from an apparent severe T. parva infection in the field and confirmed to be positive by PCR, all became negative before they were used in the transmission experiments. Ticks derived from these cattle were used to infect susceptible bovines but only T. taurotragi was transmitted. The xeno-diagnosis failed to demonstrate the carrier state in these field cattle. The five Corridor disease recovered cattle obtained from different study locations mentioned above, received lethal challenge using T. parva buffalo-derived stabilate. All challenged animals, including the susceptible control, showed schizont parasitosis as detected by the T. parva</i. real-time PCR test starting day 11 to 23. All animals also developed significant antibody titer to T. parva by day 28. Of the field cattle, only one bovine which showed mild reactions manifested by high temperature on day 11 for two consecutive days and schizonts parasitosis in lymph nodes on day 15 for only two days and recovered. The rest of the field cattle did not show any clinical or parasitological reactions during the observation period (103 days). The control bovine had high fever and showed schizonts parasitosis by day 11 for seven consecutive days. The reaction was classified as severe and had to be treated. Unfed R. appendiculatus collected off grass from one of the study sites were applied to feed on a susceptible bovine and only T. taurotragi was transmitted. There were no apparent clinical signs and the animal behavior kept normal during the observation period (60 days). This study suggests that Corridor disease should be considered as an “emerging disease” and more stringent control methods should be implemented. Copyright / Dissertation (MSc)--University of Pretoria, 2012. / Veterinary Tropical Diseases / unrestricted
555

Socio-economic impact of the participatory and conventionally implemented irrigation and livestock development projects: a case of Beitbridge and Mberengwa Districts of Zimbabwe

Ndou, Portia January 2008 (has links)
The purpose of this study was to evaluate the impact of participatory and conventional approaches to livestock and irrigation project implementation in Zimbabwe’s Beitbridge and Mberengwa districts. The conventional livestock projects performed better than the participatory. Despite the breed for the participatory livestock projects being unsuitable for the environment, the farmers failed to utilize the drugs and surplus funding set aside for replacement of dead cattle. Farmer training was found to be of paramount importance in the establishment of the livestock projects in spite of the participatory approach used for the implementation of the projects. Also the technical backup and support for the livestock project beneficiaries is important to ensure early rectification of problems that may affect the smooth running of the projects as well as an opportunity to introduce new technical advice to boost production. Livestock projects take long period of time to establish, i.e. for the financial turn over to be realized. It takes long time for farmers in these projects to make investments from the proceeds of the livestock projects. For this reason, there is need for the number of beneficiaries for each pass-on livestock project to take into account the number of beasts at project establishment and also the number per each beneficiary group. However, the projects should still be encouraged as they will take full operation at a later stage and be of benefit to the rural disadvantaged who cannot access other means to own cattle, which in turn play a pivotal role in crop production (through draft power, manure provision) and cash earnings that indirectly ensures food security. Regardless of approach used, livestock projects should be strongly supported because the districts under study are prone to poor crop production and hence the cattle can be a source of income and food. Participatory irrigation projects performed better than the conventionally implemented, despite their small hectarages. This proved that farmer participation can greatly improve the efficiency of development work and eliminate many of the problems regarding proprietorship and enhance development activities at community level. Conventional irrigation projects were plagued by problems of mismanagement and theft as was reflected by poor performance and malfunction of the conventional Chingechuru and Chimwe-Chegato irrigation schemes. Fencing theft atChingechuru irrigation scheme had brought it to a stand still. However, the larger incomes associated with the conventionally implemented irrigation projects were the result of the larger areas under cropping for these projects. Production levels in participatory irrigation schemes were good. Adoption of most technical innovations in livestock projects was found to be associated with the conventional approach. Asset procurement was a function of the farmer’s accessibility to non-project income, like formal employment, and procurement of specific assets applied more to project type than the approach to project implementation. This study found that the approach used in implementation had a greater influence on the performance of irrigation projects than livestock projects.
556

Effect of pre-slaughter stress of pigs on the levels of cortisol, creatine kinase and their subsequent relationship with pork quality

Nzolo, Jama January 2014 (has links)
The study was conducted to determine the effect of pre-slaughter stress of pigs on the levels of cortisol, creatine kinase (CK) and their subsequent relationship with pork quality. From our knowledge, there is paucity of information on transportation, lairage duration and sex effects on saliva cortisol and its relation with serum cortisol, urine cortisol and other meat quality traits. Stage one of the study assessed the effect of sex and time to slaughter (transport and lairage duration) on the levels of cortisol and CK in crossbred pigs. The second stage of the study evaluated the effect of sex and lairage duration on pork quality. The trials comprised of 60 22-weeks old commercial crossbred pigs [(30 boars vs. 30 gilts) with an average body weight of 76.9kg for gilts and 78.3kg for boars. Thirty pigs (15 Boars vs. 15 Gilts) were slaughtered on arrival after a 120km road journey and the other 30, after travelling the same road and distance, were slaughtered after having been in the lairage for 20 hours. Saliva samples were obtained during three time periods: between 07:00-10:00 on the day before the journey, on arrival at the abattoir and after lairage. Levels of cortisol in serum and urine and CK in serum samples collected at slaughter were determined. The samples (saliva and serum) were centrifuged at 20oC for 10 min at 3550 x g and stored at -20oC in separate vials until analysis. Pork quality was assessed using muscle pH, colour, thawing and cooking losses and Warner-Bratzler Shear Force. Correlations between cortisol levels in saliva, serum and urine and meat quality were assessed. The effect of sex and time to slaughter on saliva cortisol was significant. Statistical analysis showed significant interaction of sex by time to slaughter on serum cortisol. It was only the effect of sex that demonstrated higher (P <0.05) serum creatine kinase levels in gilts. Likewise, urine cortisol was influenced (P <0.05) only by time to slaughter. Saliva cortisol after transportation (r = 0.52) was correlated (P <0.05) with urine cortisol. The study suggests that there are greater responses of the Hypothalamic-pituitary-adrenal axis following time to slaughter (transport and lairage duration) between gilts and boars. This can be used in measuring cortisol in saliva, serum and urine, and serum creatine kinase to determine stress levels in pigs. Besides the lightness (L*) colour value which was significantly lower (P <0.05) in meat from gilts than from boars, the results of this study showed no interaction or individual effect (sex or lairage duration) on pH and other colour measurements. Meat cooking loss was affected (P <0.05) by gender x lairage interaction. Effect of lairage duration (as an individual effect) on the measured meat quality traits was not significant (P <0.05). Correlation analysis showed significant (P <0.05) negative relation between baseline saliva cortisol (r = -0.40) and the pork L* value. Saliva cortisol after lairage duration (r = -0.38 and r = 0.38) was correlated (P <0.05) with pH45 and pork a* value, respectively. Serum cortisol (r = -0.35) was negatively correlated (P <0.05) with pH45. Moreover, there were negative correlations (P <0.05) between saliva cortisol after transportation (r = -0.35), saliva cortisol after lairage duration (r = -0.44), serum cortisol (r = -0.40) and meat cooking loss. The study suggests that cortisol in saliva and serum can be used to determine effect of time to slaughter (transport and lairage duration) on meat quality traits from gilts and boars. Keywords: Boars; gilts; saliva cortisol; serum cortisol; serum creatine kinase; urine cortisol.
557

Etude de la gestion du bétail à l'aide de la méthode des micro-usures dentaires dans le Midi méditerranéen entre l'âge du Bronze et la période gallo-romaine. / Study of the livestock management using the microwear method in the mediterranean south between Bronze Age and Gallo-Roman period.

Rieau, Cyrille 20 November 2014 (has links)
Les micro-usures dentaires sont un outil permettant la reconstitution des régimes alimentaires de nombreuses espèces, notamment les herbivores. L'efficacité de cette méthode a été prouvée dans le cas d'espèces sauvages, mais peu d'études ont été effectuées sur des populations domestiques. L'interprétation des résultats repose sur des référentiels qui n'existent pas en contexte domestique, où l'alimentation des troupeaux est influencée par l'éleveur. La création de ce référentiel est nécessaire pour interpréter les résultats d'espèces domestiques, et notamment en archéologie pour étudier les modes de gestion des troupeaux d'espèces herbivores de la triade domestique (bovin, ovin et caprin). Sa création est l'objectif de cette étude, avant son application à des ensembles archéologiques de trois sites du sud de la France, Lattara, le Castellas et les Terriers. Le référentiel a mis en évidence une influence climatique forte à l'échelle du continent européen, tandis qu'à l'échelle du site des facteurs anthropiques ou saisonniers sont observés. L'étude des restes des sites archéologiques montre des modes d'élevage extensifs, avec des zones d'alimentation distinctes entre les troupeaux de caprinés et de bovins. Une évolution dans l'alimentation des bovins s'observe au troisième siècle avant notre ère à Lattara uniquement, liée à une probable réorganisation économique et donc agropastorale, en relation avec une forte augmentation démographique. Un élevage à deux échelles, familiale et tournée vers le commerce est envisagé à partir de cette période. Enfin certains assemblages semblent indiquer des abattages sur des intervalles temporels réduits. / Dental micro-wear is a tool for the reconstruction of diets of many species, including herbivores. The effectiveness of this method has been proven for many wild species, but few studies have been conducted on domestic populations. Interpretation of results for wild species is based on database that do not exist in domestic context, where feeding of herds is influenced by the herder. Creation of this database is necessary to interpret results of domestic species, especially in archaeology to study the management of herds of herbivorous species of the domestic triad (cattle, sheep and goat). Its creation is the main object of this study, before its application to teeth remains of three archaeological sites from southern France, Lattara, le Castellas and les Terriers. The database has highlighted a strong climatic influence at the European scale, while at the level of the site other factors including anthropogenic choices or seasonality are observed. The study of archaeological samples from the sites revealed extensive management with feeding areas separated from the herds of cattle and caprine. An evolution in alimentation of cattle is seen in the third century BCE in Lattara only, probably related to an economic reorganization and so agropastoral, in connection with a strong demographic growth. A two-scales breeding, family and trade oriented is thought for this period. Finally, some data sets suggest slaughters in reduced temporal intervals.
558

Principles of Obtaining and Interpreting Utilization Data on Rangelands

Ruyle, George B., Smith, Lamar, Maynard, Jim, Barker, Steve, Stewart, Dave, Meyer, Walt, Couloudon, Bill, Williams, Stephen 10 1900 (has links)
14 pp. / Originally published: 2007 / A primary expression of stocking levels on rangeland vegetation is utilization defined as the proportion or degree of current years forage production that is consumed or destroyed by animals (including insects). Utilization may refer either to a single plant species, a group of species, or the vegetation as a whole. Utilization is an important factor in influencing changes in the soil, water, animal, and vegetation resources. The impact of a specific intensity of use on a plant species is highly variable depending on past and present use, period of use, duration of use, inter-specific competition, weather, availability of soil moisture for regrowth, and how these factors interact. Utilization data can be used as a guideline for moving livestock within an allotment with due consideration to season, weather conditions and the availability of forage and water in pastures scheduled for use during the same grazing season. In combination with actual use and climatic data, utilization measurements on key areas and utilization pattern mapping are useful for estimating proper stocking levels under current management. Utilization studies are helpful in identifying key and problem areas, and in identifying range improvements needed to improve livestock distribution. Reviewed 10/2016. Originally published 5/2007.
559

Analýza pojištění zvířat na českém pojistném trhu / Analysis of animal insurance on the Czech insurance market

Kabrnová, Barbora January 2011 (has links)
This work deals with animal insurance, both livestock insurance and pet insurance. It is important to describe risks and emphasize role of insurance as one of the best ways to eliminate the high cost of animal breeding. Therefore, the work outlines the importance of insurance, current situation and expected future developments, as well as a very important support from the state and other institutions. All kind of private animal insurance, that are offered on our insurance market at present, are characterized in this work. It is the cost of veterinary fees insurance, death and euthanasia insurance, third party liability and pet travel insurance. The work analyzes the current situation and offer insurers on the Czech insurance market. Part of this work is dedicated to comparison of products and overall evaluation. On the basis of gained calculations and other information this work contains an illustrative examples, which brings view of situation on the market and comprehensive products comparison of insurance companies.
560

The extent of acaricide resistance in the eastern region of the Eastern Cape Province

Ntondini, Zoleka 16 July 2009 (has links)
The control of ticks, and to some extent tick-borne diseases, over much of South Africa is currently dependent on acaricides and will probably remain so for the foreseeable future. Resistance to these chemicals by ticks thus poses a major threat to the livestock industry especially as these chemicals constitute an ever-diminishing resource with fewer being discovered and the cost of their development becoming prohibitive. In order to determine the extent of acaricide resistance in the eastern region of the Eastern Cape Province one-, two- and three-host ticks were collected from cattle at 58 dip-tanks over a period of 2 years. The one-host tick selected was Rhipicephalus (Boophilus) microplus, the two-host tick Rhipicephalus evertsi evertsi and the three-host tick Rhipicephalus appendiculatus. The ticks were tested for resistance to three compounds, namely amitraz, cypermethrin and chlorfenvinphos. The Shaw Larval Immersion Test detected emerging resistance to amitraz in the one-host tick R. (Boophilus) microplus at two dip-tanks and resistance at a third. It also revealed resistance in this tick to cypermethrin at one dip-tank, and emerging resistance to chlorfenvinphos at eight dip-tanks and resistance at two. The two-host tick R. evertsi evertsi was susceptible to amitraz and cypermethrin at all dip-tanks, but showed emerging resistance to chlorfenvinphos at seven dip-tanks and resistance at four. The three-host tick R. appendiculatus was susceptible to amitraz and chlorfenvinphos at all dip-tanks and demonstrated emerging resistance to cypermethrin at one. With the exception of R. (Boophilus) microplus, in which emerging resistance to amitraz was detected at one dip-tank by the Reproductive Estimate Test, all three tick species at all dip-tanks at which sufficient numbers of ticks had been collected, were susceptible to the three acaracides in both the Egg Laying Test and the Reproductive Estimate Test. Thus despite its fairly long and widespread use in the eastern region of the Eastern Cape Province very little or no resistance to amitraz was detected in three tick species regularly encountered on cattle in this region, namely R. (Boophilus) microplus, R. evertsi evertsi and R. appendiculatus. On the other hand resistance to chlorfenvinphos was detected in both R. (Boophilus) microplus and R. evertsi evertsi at a number of dip-tanks even though it, or other organophosphorous-based compounds, had probably not been used for tick control in the region for a number of years. The localities at which ticks were collected had already been mapped and the localities at which acaricide resistant ticks were encountered were mapped during this study. The three tick species that were targeted for acaricide resistance testing were widespread throughout the study region, but no pattern of geographic distribution for the acaricide resistant strains of these species that were detected, emerged. The rapidity of selection for acaricide resistance appeared to be closely related to the life cycles of the three ticks and the number of days that they theoretically would spend annually on their preferred host animals. Thus a greater number of acaricide resistant strains were encountered amongst the one-host tickR. (Boophilus) microplus and the two-host tick R. evertsi evertsi than the three-host tick R. appendiculatus. The fist two ticks both complete more than one life cycle a year and hence spend a longer time on their cattle hosts than the three-host tick R. appendiculatus, which completes only one life cycle a year and in addition is a rapid feeder in all its stages of development. To counter selection for acaricide resistance it is proposed that regular testing for resistance should be carried out, and that as soon as emerging resistance is detected in ticks on cattle at a particular dip-tank, that the acaricide in use at that dip-tank should be changed to a compound belonging to a completely different group of chemicals. Copyright / Dissertation (MSc)--University of Pretoria, 2009. / Veterinary Tropical Diseases / unrestricted

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